FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_clock.c

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 1982, 1986, 1991, 1993
      *      The Regents of the University of California.  All rights reserved.
      * (c) UNIX System Laboratories, Inc.
      * All or some portions of this file are derived from material licensed
      * to the University of California by American Telephone and Telegraph
      * Co. or Unix System Laboratories, Inc. and are reproduced herein with
     * the permission of UNIX System Laboratories, Inc.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)kern_clock.c        8.5 (Berkeley) 1/21/94
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include "opt_kdb.h"
    #include "opt_device_polling.h"
    #include "opt_hwpmc_hooks.h"
    #include "opt_ntp.h"
    #include "opt_watchdog.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/callout.h>
    #include <sys/epoch.h>
    #include <sys/eventhandler.h>
    #include <sys/gtaskqueue.h>
    #include <sys/kdb.h>
    #include <sys/kernel.h>
    #include <sys/kthread.h>
    #include <sys/ktr.h>
    #include <sys/lock.h>
    #include <sys/mutex.h>
    #include <sys/proc.h>
    #include <sys/resource.h>
    #include <sys/resourcevar.h>
    #include <sys/sched.h>
    #include <sys/sdt.h>
    #include <sys/signalvar.h>
    #include <sys/sleepqueue.h>
    #include <sys/smp.h>
    #include <vm/vm.h>
    #include <vm/pmap.h>
    #include <vm/vm_map.h>
    #include <sys/sysctl.h>
    #include <sys/bus.h>
    #include <sys/interrupt.h>
    #include <sys/limits.h>
    #include <sys/timetc.h>
    
    #ifdef HWPMC_HOOKS
    #include <sys/pmckern.h>
    PMC_SOFT_DEFINE( , , clock, hard);
    PMC_SOFT_DEFINE( , , clock, stat);
    PMC_SOFT_DEFINE_EX( , , clock, prof, \
        cpu_startprofclock, cpu_stopprofclock);
    #endif
    
    #ifdef DEVICE_POLLING
    extern void hardclock_device_poll(void);
    #endif /* DEVICE_POLLING */
    
    /* Spin-lock protecting profiling statistics. */
    static struct mtx time_lock;
    
    SDT_PROVIDER_DECLARE(sched);
    SDT_PROBE_DEFINE2(sched, , , tick, "struct thread *", "struct proc *");
    
    static int
    sysctl_kern_cp_time(SYSCTL_HANDLER_ARGS)
    {
            int error;
            long cp_time[CPUSTATES];
   #ifdef SCTL_MASK32
           int i;
           unsigned int cp_time32[CPUSTATES];
   #endif
   
           read_cpu_time(cp_time);
   #ifdef SCTL_MASK32
           if (req->flags & SCTL_MASK32) {
                   if (!req->oldptr)
                           return SYSCTL_OUT(req, 0, sizeof(cp_time32));
                   for (i = 0; i < CPUSTATES; i++)
                           cp_time32[i] = (unsigned int)cp_time[i];
                   error = SYSCTL_OUT(req, cp_time32, sizeof(cp_time32));
           } else
   #endif
           {
                   if (!req->oldptr)
                           return SYSCTL_OUT(req, 0, sizeof(cp_time));
                   error = SYSCTL_OUT(req, cp_time, sizeof(cp_time));
           }
           return error;
   }
   
   SYSCTL_PROC(_kern, OID_AUTO, cp_time, CTLTYPE_LONG|CTLFLAG_RD|CTLFLAG_MPSAFE,
       0,0, sysctl_kern_cp_time, "LU", "CPU time statistics");
   
   static long empty[CPUSTATES];
   
   static int
   sysctl_kern_cp_times(SYSCTL_HANDLER_ARGS)
   {
           struct pcpu *pcpu;
           int error;
           int c;
           long *cp_time;
   #ifdef SCTL_MASK32
           unsigned int cp_time32[CPUSTATES];
           int i;
   #endif
   
           if (!req->oldptr) {
   #ifdef SCTL_MASK32
                   if (req->flags & SCTL_MASK32)
                           return SYSCTL_OUT(req, 0, sizeof(cp_time32) * (mp_maxid + 1));
                   else
   #endif
                           return SYSCTL_OUT(req, 0, sizeof(long) * CPUSTATES * (mp_maxid + 1));
           }
           for (error = 0, c = 0; error == 0 && c <= mp_maxid; c++) {
                   if (!CPU_ABSENT(c)) {
                           pcpu = pcpu_find(c);
                           cp_time = pcpu->pc_cp_time;
                   } else {
                           cp_time = empty;
                   }
   #ifdef SCTL_MASK32
                   if (req->flags & SCTL_MASK32) {
                           for (i = 0; i < CPUSTATES; i++)
                                   cp_time32[i] = (unsigned int)cp_time[i];
                           error = SYSCTL_OUT(req, cp_time32, sizeof(cp_time32));
                   } else
   #endif
                           error = SYSCTL_OUT(req, cp_time, sizeof(long) * CPUSTATES);
           }
           return error;
   }
   
   SYSCTL_PROC(_kern, OID_AUTO, cp_times, CTLTYPE_LONG|CTLFLAG_RD|CTLFLAG_MPSAFE,
       0,0, sysctl_kern_cp_times, "LU", "per-CPU time statistics");
   
   #ifdef DEADLKRES
   static const char *blessed[] = {
           "getblk",
           "so_snd_sx",
           "so_rcv_sx",
           NULL
   };
   static int slptime_threshold = 1800;
   static int blktime_threshold = 900;
   static int sleepfreq = 3;
   
   static void
   deadlres_td_on_lock(struct proc *p, struct thread *td, int blkticks)
   {
           int tticks;
   
           sx_assert(&allproc_lock, SX_LOCKED);
           PROC_LOCK_ASSERT(p, MA_OWNED);
           THREAD_LOCK_ASSERT(td, MA_OWNED);
           /*
            * The thread should be blocked on a turnstile, simply check
            * if the turnstile channel is in good state.
            */
           MPASS(td->td_blocked != NULL);
   
           tticks = ticks - td->td_blktick;
           if (tticks > blkticks)
                   /*
                    * Accordingly with provided thresholds, this thread is stuck
                    * for too long on a turnstile.
                    */
                   panic("%s: possible deadlock detected for %p (%s), "
                       "blocked for %d ticks\n", __func__,
                       td, sched_tdname(td), tticks);
   }
   
   static void
   deadlres_td_sleep_q(struct proc *p, struct thread *td, int slpticks)
   {
           const void *wchan;
           int i, slptype, tticks;
   
           sx_assert(&allproc_lock, SX_LOCKED);
           PROC_LOCK_ASSERT(p, MA_OWNED);
           THREAD_LOCK_ASSERT(td, MA_OWNED);
           /*
            * Check if the thread is sleeping on a lock, otherwise skip the check.
            * Drop the thread lock in order to avoid a LOR with the sleepqueue
            * spinlock.
            */
           wchan = td->td_wchan;
           tticks = ticks - td->td_slptick;
           slptype = sleepq_type(wchan);
           if ((slptype == SLEEPQ_SX || slptype == SLEEPQ_LK) &&
               tticks > slpticks) {
                   /*
                    * Accordingly with provided thresholds, this thread is stuck
                    * for too long on a sleepqueue.
                    * However, being on a sleepqueue, we might still check for the
                    * blessed list.
                    */
                   for (i = 0; blessed[i] != NULL; i++)
                           if (!strcmp(blessed[i], td->td_wmesg))
                                   return;
   
                   panic("%s: possible deadlock detected for %p (%s), "
                       "blocked for %d ticks\n", __func__,
                       td, sched_tdname(td), tticks);
           }
   }
   
   static void
   deadlkres(void)
   {
           struct proc *p;
           struct thread *td;
           int blkticks, slpticks, tryl;
   
           tryl = 0;
           for (;;) {
                   blkticks = blktime_threshold * hz;
                   slpticks = slptime_threshold * hz;
   
                   /*
                    * Avoid to sleep on the sx_lock in order to avoid a
                    * possible priority inversion problem leading to
                    * starvation.
                    * If the lock can't be held after 100 tries, panic.
                    */
                   if (!sx_try_slock(&allproc_lock)) {
                           if (tryl > 100)
                                   panic("%s: possible deadlock detected "
                                       "on allproc_lock\n", __func__);
                           tryl++;
                           pause("allproc", sleepfreq * hz);
                           continue;
                   }
                   tryl = 0;
                   FOREACH_PROC_IN_SYSTEM(p) {
                           PROC_LOCK(p);
                           if (p->p_state == PRS_NEW) {
                                   PROC_UNLOCK(p);
                                   continue;
                           }
                           FOREACH_THREAD_IN_PROC(p, td) {
                                   thread_lock(td);
                                   if (TD_ON_LOCK(td))
                                           deadlres_td_on_lock(p, td,
                                               blkticks);
                                   else if (TD_IS_SLEEPING(td))
                                           deadlres_td_sleep_q(p, td,
                                               slpticks);
                                   thread_unlock(td);
                           }
                           PROC_UNLOCK(p);
                   }
                   sx_sunlock(&allproc_lock);
   
                   /* Sleep for sleepfreq seconds. */
                   pause("-", sleepfreq * hz);
           }
   }
   
   static struct kthread_desc deadlkres_kd = {
           "deadlkres",
           deadlkres,
           (struct thread **)NULL
   };
   
   SYSINIT(deadlkres, SI_SUB_CLOCKS, SI_ORDER_ANY, kthread_start, &deadlkres_kd);
   
   static SYSCTL_NODE(_debug, OID_AUTO, deadlkres, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
       "Deadlock resolver");
   SYSCTL_INT(_debug_deadlkres, OID_AUTO, slptime_threshold, CTLFLAG_RW,
       &slptime_threshold, 0,
       "Number of seconds within is valid to sleep on a sleepqueue");
   SYSCTL_INT(_debug_deadlkres, OID_AUTO, blktime_threshold, CTLFLAG_RW,
       &blktime_threshold, 0,
       "Number of seconds within is valid to block on a turnstile");
   SYSCTL_INT(_debug_deadlkres, OID_AUTO, sleepfreq, CTLFLAG_RW, &sleepfreq, 0,
       "Number of seconds between any deadlock resolver thread run");
   #endif  /* DEADLKRES */
   
   void
   read_cpu_time(long *cp_time)
   {
           struct pcpu *pc;
           int i, j;
   
           /* Sum up global cp_time[]. */
           bzero(cp_time, sizeof(long) * CPUSTATES);
           CPU_FOREACH(i) {
                   pc = pcpu_find(i);
                   for (j = 0; j < CPUSTATES; j++)
                           cp_time[j] += pc->pc_cp_time[j];
           }
   }
   
   #include <sys/watchdog.h>
   
   static int watchdog_ticks;
   static int watchdog_enabled;
   static void watchdog_fire(void);
   static void watchdog_config(void *, u_int, int *);
   
   static void
   watchdog_attach(void)
   {
           EVENTHANDLER_REGISTER(watchdog_list, watchdog_config, NULL, 0);
   }
   
   /*
    * Clock handling routines.
    *
    * This code is written to operate with two timers that run independently of
    * each other.
    *
    * The main timer, running hz times per second, is used to trigger interval
    * timers, timeouts and rescheduling as needed.
    *
    * The second timer handles kernel and user profiling,
    * and does resource use estimation.  If the second timer is programmable,
    * it is randomized to avoid aliasing between the two clocks.  For example,
    * the randomization prevents an adversary from always giving up the cpu
    * just before its quantum expires.  Otherwise, it would never accumulate
    * cpu ticks.  The mean frequency of the second timer is stathz.
    *
    * If no second timer exists, stathz will be zero; in this case we drive
    * profiling and statistics off the main clock.  This WILL NOT be accurate;
    * do not do it unless absolutely necessary.
    *
    * The statistics clock may (or may not) be run at a higher rate while
    * profiling.  This profile clock runs at profhz.  We require that profhz
    * be an integral multiple of stathz.
    *
    * If the statistics clock is running fast, it must be divided by the ratio
    * profhz/stathz for statistics.  (For profiling, every tick counts.)
    *
    * Time-of-day is maintained using a "timecounter", which may or may
    * not be related to the hardware generating the above mentioned
    * interrupts.
    */
   
   int     stathz;
   int     profhz;
   int     profprocs;
   volatile int    ticks;
   int     psratio;
   
   DPCPU_DEFINE_STATIC(int, pcputicks);    /* Per-CPU version of ticks. */
   #ifdef DEVICE_POLLING
   static int devpoll_run = 0;
   #endif
   
   static void
   ast_oweupc(struct thread *td, int tda __unused)
   {
           if ((td->td_proc->p_flag & P_PROFIL) == 0)
                   return;
           addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
           td->td_profil_ticks = 0;
           td->td_pflags &= ~TDP_OWEUPC;
   }
   
   static void
   ast_alrm(struct thread *td, int tda __unused)
   {
           struct proc *p;
   
           p = td->td_proc;
           PROC_LOCK(p);
           kern_psignal(p, SIGVTALRM);
           PROC_UNLOCK(p);
   }
   
   static void
   ast_prof(struct thread *td, int tda __unused)
   {
           struct proc *p;
   
           p = td->td_proc;
           PROC_LOCK(p);
           kern_psignal(p, SIGPROF);
           PROC_UNLOCK(p);
   }
   
   /*
    * Initialize clock frequencies and start both clocks running.
    */
   static void
   initclocks(void *dummy __unused)
   {
           int i;
   
           /*
            * Set divisors to 1 (normal case) and let the machine-specific
            * code do its bit.
            */
           mtx_init(&time_lock, "time lock", NULL, MTX_DEF);
           cpu_initclocks();
   
           /*
            * Compute profhz/stathz, and fix profhz if needed.
            */
           i = stathz ? stathz : hz;
           if (profhz == 0)
                   profhz = i;
           psratio = profhz / i;
   
           ast_register(TDA_OWEUPC, ASTR_ASTF_REQUIRED, 0, ast_oweupc);
           ast_register(TDA_ALRM, ASTR_ASTF_REQUIRED, 0, ast_alrm);
           ast_register(TDA_PROF, ASTR_ASTF_REQUIRED, 0, ast_prof);
   
   #ifdef SW_WATCHDOG
           /* Enable hardclock watchdog now, even if a hardware watchdog exists. */
           watchdog_attach();
   #else
           /* Volunteer to run a software watchdog. */
           if (wdog_software_attach == NULL)
                   wdog_software_attach = watchdog_attach;
   #endif
   }
   SYSINIT(clocks, SI_SUB_CLOCKS, SI_ORDER_FIRST, initclocks, NULL);
   
   static __noinline void
   hardclock_itimer(struct thread *td, struct pstats *pstats, int cnt, int usermode)
   {
           struct proc *p;
           int ast;
   
           ast = 0;
           p = td->td_proc;
           if (usermode &&
               timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
                   PROC_ITIMLOCK(p);
                   if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL],
                       tick * cnt) == 0)
                           ast |= TDAI(TDA_ALRM);
                   PROC_ITIMUNLOCK(p);
           }
           if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
                   PROC_ITIMLOCK(p);
                   if (itimerdecr(&pstats->p_timer[ITIMER_PROF],
                       tick * cnt) == 0)
                           ast |= TDAI(TDA_PROF);
                   PROC_ITIMUNLOCK(p);
           }
           if (ast != 0)
                   ast_sched_mask(td, ast);
   }
   
   void
   hardclock(int cnt, int usermode)
   {
           struct pstats *pstats;
           struct thread *td = curthread;
           struct proc *p = td->td_proc;
           int *t = DPCPU_PTR(pcputicks);
           int global, i, newticks;
   
           /*
            * Update per-CPU and possibly global ticks values.
            */
           *t += cnt;
           global = ticks;
           do {
                   newticks = *t - global;
                   if (newticks <= 0) {
                           if (newticks < -1)
                                   *t = global - 1;
                           newticks = 0;
                           break;
                   }
           } while (!atomic_fcmpset_int(&ticks, &global, *t));
   
           /*
            * Run current process's virtual and profile time, as needed.
            */
           pstats = p->p_stats;
           if (__predict_false(
               timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) ||
               timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)))
                   hardclock_itimer(td, pstats, cnt, usermode);
   
   #ifdef  HWPMC_HOOKS
           if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
                   PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);
           if (td->td_intr_frame != NULL)
                   PMC_SOFT_CALL_TF( , , clock, hard, td->td_intr_frame);
   #endif
           /* We are in charge to handle this tick duty. */
           if (newticks > 0) {
                   tc_ticktock(newticks);
   #ifdef DEVICE_POLLING
                   /* Dangerous and no need to call these things concurrently. */
                   if (atomic_cmpset_acq_int(&devpoll_run, 0, 1)) {
                           /* This is very short and quick. */
                           hardclock_device_poll();
                           atomic_store_rel_int(&devpoll_run, 0);
                   }
   #endif /* DEVICE_POLLING */
                   if (watchdog_enabled > 0) {
                           i = atomic_fetchadd_int(&watchdog_ticks, -newticks);
                           if (i > 0 && i <= newticks)
                                   watchdog_fire();
                   }
                   intr_event_handle(clk_intr_event, NULL);
           }
           if (curcpu == CPU_FIRST())
                   cpu_tick_calibration();
           if (__predict_false(DPCPU_GET(epoch_cb_count)))
                   GROUPTASK_ENQUEUE(DPCPU_PTR(epoch_cb_task));
   }
   
   void
   hardclock_sync(int cpu)
   {
           int *t;
           KASSERT(!CPU_ABSENT(cpu), ("Absent CPU %d", cpu));
           t = DPCPU_ID_PTR(cpu, pcputicks);
   
           *t = ticks;
   }
   
   /*
    * Regular integer scaling formula without losing precision:
    */
   #define TIME_INT_SCALE(value, mul, div) \
           (((value) / (div)) * (mul) + (((value) % (div)) * (mul)) / (div))
   
   /*
    * Macro for converting seconds and microseconds into actual ticks,
    * based on the given hz value:
    */
   #define TIME_TO_TICKS(sec, usec, hz) \
           ((sec) * (hz) + TIME_INT_SCALE(usec, hz, 1 << 6) / (1000000 >> 6))
   
   #define TIME_ASSERT_VALID_HZ(hz)        \
           _Static_assert(TIME_TO_TICKS(INT_MAX / (hz) - 1, 999999, hz) >= 0 && \
                          TIME_TO_TICKS(INT_MAX / (hz) - 1, 999999, hz) < INT_MAX, \
                          "tvtohz() can overflow the regular integer type")
   
   /*
    * Compile time assert the maximum and minimum values to fit into a
    * regular integer when computing TIME_TO_TICKS():
    */
   TIME_ASSERT_VALID_HZ(HZ_MAXIMUM);
   TIME_ASSERT_VALID_HZ(HZ_MINIMUM);
   
   /*
    * The formula is mostly linear, but test some more common values just
    * in case:
    */
   TIME_ASSERT_VALID_HZ(1024);
   TIME_ASSERT_VALID_HZ(1000);
   TIME_ASSERT_VALID_HZ(128);
   TIME_ASSERT_VALID_HZ(100);
   
   /*
    * Compute number of ticks representing the specified amount of time.
    * If the specified time is negative, a value of 1 is returned. This
    * function returns a value from 1 up to and including INT_MAX.
    */
   int
   tvtohz(struct timeval *tv)
   {
           int retval;
   
           /*
            * The values passed here may come from user-space and these
            * checks ensure "tv_usec" is within its allowed range:
            */
   
           /* check for tv_usec underflow */
           if (__predict_false(tv->tv_usec < 0)) {
                   tv->tv_sec += tv->tv_usec / 1000000;
                   tv->tv_usec = tv->tv_usec % 1000000;
                   /* convert tv_usec to a positive value */
                   if (__predict_true(tv->tv_usec < 0)) {
                           tv->tv_usec += 1000000;
                           tv->tv_sec -= 1;
                   }
           /* check for tv_usec overflow */
           } else if (__predict_false(tv->tv_usec >= 1000000)) {
                   tv->tv_sec += tv->tv_usec / 1000000;
                   tv->tv_usec = tv->tv_usec % 1000000;
           }
   
           /* check for tv_sec underflow */
           if (__predict_false(tv->tv_sec < 0))
                   return (1);
           /* check for tv_sec overflow (including room for the tv_usec part) */
           else if (__predict_false(tv->tv_sec >= tick_seconds_max))
                   return (INT_MAX);
   
           /* cast to "int" to avoid platform differences */
           retval = TIME_TO_TICKS((int)tv->tv_sec, (int)tv->tv_usec, hz);
   
           /* add one additional tick */
           return (retval + 1);
   }
   
   /*
    * Start profiling on a process.
    *
    * Kernel profiling passes proc0 which never exits and hence
    * keeps the profile clock running constantly.
    */
   void
   startprofclock(struct proc *p)
   {
   
           PROC_LOCK_ASSERT(p, MA_OWNED);
           if (p->p_flag & P_STOPPROF)
                   return;
           if ((p->p_flag & P_PROFIL) == 0) {
                   p->p_flag |= P_PROFIL;
                   mtx_lock(&time_lock);
                   if (++profprocs == 1)
                           cpu_startprofclock();
                   mtx_unlock(&time_lock);
           }
   }
   
   /*
    * Stop profiling on a process.
    */
   void
   stopprofclock(struct proc *p)
   {
   
           PROC_LOCK_ASSERT(p, MA_OWNED);
           if (p->p_flag & P_PROFIL) {
                   if (p->p_profthreads != 0) {
                           while (p->p_profthreads != 0) {
                                   p->p_flag |= P_STOPPROF;
                                   msleep(&p->p_profthreads, &p->p_mtx, PPAUSE,
                                       "stopprof", 0);
                           }
                   }
                   if ((p->p_flag & P_PROFIL) == 0)
                           return;
                   p->p_flag &= ~P_PROFIL;
                   mtx_lock(&time_lock);
                   if (--profprocs == 0)
                           cpu_stopprofclock();
                   mtx_unlock(&time_lock);
           }
   }
   
   /*
    * Statistics clock.  Updates rusage information and calls the scheduler
    * to adjust priorities of the active thread.
    *
    * This should be called by all active processors.
    */
   void
   statclock(int cnt, int usermode)
   {
           struct rusage *ru;
           struct vmspace *vm;
           struct thread *td;
           struct proc *p;
           long rss;
           long *cp_time;
           uint64_t runtime, new_switchtime;
   
           td = curthread;
           p = td->td_proc;
   
           cp_time = (long *)PCPU_PTR(cp_time);
           if (usermode) {
                   /*
                    * Charge the time as appropriate.
                    */
                   td->td_uticks += cnt;
                   if (p->p_nice > NZERO)
                           cp_time[CP_NICE] += cnt;
                   else
                           cp_time[CP_USER] += cnt;
           } else {
                   /*
                    * Came from kernel mode, so we were:
                    * - handling an interrupt,
                    * - doing syscall or trap work on behalf of the current
                    *   user process, or
                    * - spinning in the idle loop.
                    * Whichever it is, charge the time as appropriate.
                    * Note that we charge interrupts to the current process,
                    * regardless of whether they are ``for'' that process,
                    * so that we know how much of its real time was spent
                    * in ``non-process'' (i.e., interrupt) work.
                    */
                   if ((td->td_pflags & TDP_ITHREAD) ||
                       td->td_intr_nesting_level >= 2) {
                           td->td_iticks += cnt;
                           cp_time[CP_INTR] += cnt;
                   } else {
                           td->td_pticks += cnt;
                           td->td_sticks += cnt;
                           if (!TD_IS_IDLETHREAD(td))
                                   cp_time[CP_SYS] += cnt;
                           else
                                   cp_time[CP_IDLE] += cnt;
                   }
           }
   
           /* Update resource usage integrals and maximums. */
           MPASS(p->p_vmspace != NULL);
           vm = p->p_vmspace;
           ru = &td->td_ru;
           ru->ru_ixrss += pgtok(vm->vm_tsize) * cnt;
           ru->ru_idrss += pgtok(vm->vm_dsize) * cnt;
           ru->ru_isrss += pgtok(vm->vm_ssize) * cnt;
           rss = pgtok(vmspace_resident_count(vm));
           if (ru->ru_maxrss < rss)
                   ru->ru_maxrss = rss;
           KTR_POINT2(KTR_SCHED, "thread", sched_tdname(td), "statclock",
               "prio:%d", td->td_priority, "stathz:%d", (stathz)?stathz:hz);
           SDT_PROBE2(sched, , , tick, td, td->td_proc);
           thread_lock_flags(td, MTX_QUIET);
   
           /*
            * Compute the amount of time during which the current
            * thread was running, and add that to its total so far.
            */
           new_switchtime = cpu_ticks();
           runtime = new_switchtime - PCPU_GET(switchtime);
           td->td_runtime += runtime;
           td->td_incruntime += runtime;
           PCPU_SET(switchtime, new_switchtime);
   
           sched_clock(td, cnt);
           thread_unlock(td);
   #ifdef HWPMC_HOOKS
           if (td->td_intr_frame != NULL)
                   PMC_SOFT_CALL_TF( , , clock, stat, td->td_intr_frame);
   #endif
   }
   
   void
   profclock(int cnt, int usermode, uintfptr_t pc)
   {
           struct thread *td;
   
           td = curthread;
           if (usermode) {
                   /*
                    * Came from user mode; CPU was in user state.
                    * If this process is being profiled, record the tick.
                    * if there is no related user location yet, don't
                    * bother trying to count it.
                    */
                   if (td->td_proc->p_flag & P_PROFIL)
                           addupc_intr(td, pc, cnt);
           }
   #ifdef HWPMC_HOOKS
           if (td->td_intr_frame != NULL)
                   PMC_SOFT_CALL_TF( , , clock, prof, td->td_intr_frame);
   #endif
   }
   
   /*
    * Return information about system clocks.
    */
   static int
   sysctl_kern_clockrate(SYSCTL_HANDLER_ARGS)
   {
           struct clockinfo clkinfo;
           /*
            * Construct clockinfo structure.
            */
           bzero(&clkinfo, sizeof(clkinfo));
           clkinfo.hz = hz;
           clkinfo.tick = tick;
           clkinfo.profhz = profhz;
           clkinfo.stathz = stathz ? stathz : hz;
           return (sysctl_handle_opaque(oidp, &clkinfo, sizeof clkinfo, req));
   }
   
   SYSCTL_PROC(_kern, KERN_CLOCKRATE, clockrate,
           CTLTYPE_STRUCT|CTLFLAG_RD|CTLFLAG_MPSAFE,
           0, 0, sysctl_kern_clockrate, "S,clockinfo",
           "Rate and period of various kernel clocks");
   
   static void
   watchdog_config(void *unused __unused, u_int cmd, int *error)
   {
           u_int u;
   
           u = cmd & WD_INTERVAL;
           if (u >= WD_TO_1SEC) {
                   watchdog_ticks = (1 << (u - WD_TO_1SEC)) * hz;
                   watchdog_enabled = 1;
                   *error = 0;
           } else {
                   watchdog_enabled = 0;
           }
   }
   
   /*
    * Handle a watchdog timeout by dumping interrupt information and
    * then either dropping to DDB or panicking.
    */
   static void
   watchdog_fire(void)
   {
           int nintr;
           uint64_t inttotal;
           u_long *curintr;
           char *curname;
   
           curintr = intrcnt;
           curname = intrnames;
           inttotal = 0;
           nintr = sintrcnt / sizeof(u_long);
   
           printf("interrupt                   total\n");
           while (--nintr >= 0) {
                   if (*curintr)
                           printf("%-12s %20lu\n", curname, *curintr);
                   curname += strlen(curname) + 1;
                   inttotal += *curintr++;
           }
           printf("Total        %20ju\n", (uintmax_t)inttotal);
   
   #if defined(KDB) && !defined(KDB_UNATTENDED)
           kdb_backtrace();
           kdb_enter(KDB_WHY_WATCHDOG, "watchdog timeout");
   #else
           panic("watchdog timeout");
   #endif
   }

Cache object: 641da87ef76c250215322bd5f54b325f